Zero-Bias Conductance Through Side-Coupled Double Quantum Dots

TL;DR

This paper investigates zero-bias conductance in side-coupled double quantum dots at low temperatures, revealing phase behavior and Kondo effects using numerical renormalization group analysis.

Contribution

It provides a detailed phase diagram and analytical expressions for the Kondo regime and temperature, advancing understanding of conductance in quantum dot systems.

Findings

Localized electrons form a spin-singlet with weak conductance near particle-hole symmetry.

Enhanced conductance occurs due to the two-stage Kondo effect with two electrons.

Kondo regime with single electron occupancy shows increased conductance and specific temperature dependence.

Abstract

Low temperature zero-bias conductance through two side-coupled quantum dots is investigated using Wilson's numerical renormalization group technique. A low-temperature phase diagram is computed. Near the particle-hole symmetric point localized electrons form a spin-singlet associated with weak conductance. For weak inter-dot coupling we find enhanced conductance due to the two-stage Kondo effect when two electrons occupy quantum dots. When quantum dots are populated with a single electron, the system enters Kondo regime with enhanced conductance. Analytical expressions for the width of the Kondo regime and the Kondo temperature in this regime are given.